It is known to perform a phase difference focus detection or autofocus (“AF”) by including a focus detection pixel in image pickup pixels in an image sensor. For example, PTL 1, PTL 2, and PTL 3.
In an electronic viewfinder mode or a motion image pickup mode, the frame rate is more important than the image quality.
PTL 4 proposes an image pickup apparatus that arranges no focus detection pixel in the image sensor, and can provide an output by switching a skip readout mode (or a thinning-out readout mode) and a mixture readout mode. Since the mixture readout mode mixes signals of a plurality of pixels and uses the resultant signal, the mixture readout mode can restrain moire that would otherwise occur when an object has a high spatial frequency. The skip readout mode skips signals of some of all pixels, and thus can restrain generations of smears that would otherwise occur due to the high brightness.